The plot of Endrendrum Punnagai is said to be inspired from a few real life incidents that Director Ahmed came across. While in the writing stage of the script he felt actor Jeeva would be the most apt person for the role of the protagonist and approached him for the same. Jeeva without hesitancy accepted the role.
Director Ahmed initially did not plan to make a comedy film when he was making Endrendrum Punnagai. He only wanted to narrate the story of three friends and how their beliefs shape their lives. However once comedy actor Santhanam stepped into the project the whole film took a different shape and he brought along a lot of humor content into the movie.
A lot of the humorous scenes in the movie were not originally part of the script, however while shooting the film they extemporized and improvised on the spot and induced a lot of humor into the scenes. The director feels that is one of the main reasons that the humor worked well with the audience.